Monogamous Mating in the Aquatic World

Celebrate Valentine’s Day by learning about monogamous marine animals!

Published February 14, 2018

Puffins, French angelfish, seahorses and clownfish are among the less than 5 percent of the animal kingdom that mate for life. And although love is in the air on Valentine’s Day, it’s not necessarily in the water—this tendency to stick with the same partner is more for practicality, such as protection and efficient breeding, than romance.

After six months apart, puffins will often return to the same nesting site to copulate with the same partner year after year. Both parents take turns incubating the single egg laid by the female, and they trade off parental duties for the hatched chick, known as a puffling.

French angelfish live, travel and hunt in a pair, and spend half their lifetime swimming by their partner’s side. If a mature French angelfish is seen alone, it’s usually because their mate has passed away, and they never look for a new one. French angelfish rely on their partner to help defend their territories.

With their intertwined tails and snout-to-snout swimming method, male and female seahorses may look like a picture of devotion—but for many seahorse species, monogamy only lasts for a single breeding season. After engaging in repeated mating “dances,” the female transfers her eggs to the male’s brood pouch, where the male will fertilize the eggs and carry them to term.